Control for loom letoffs



Dec. 24, .1940. o. v. PAYNE CONTROL FOR LOOM LE'I'OFFS 2 Sheet-Sheet' 1Filed Nov. 13, 1939 |NVENTOR OSCAR V PAYNE M ATTORNEY Dec. 24, 1940. OPAYNE 2,226,232

CONTROL FOR LOOM LETOFFS Filed Nov 13, 1339 2 Sheets-Sheet 2 FIE. E

J-ruwnmron 05cm: V. PAYNE ATT O'RNEY Patented Dec. 24, 1940 UNITEDSTATES 2,226,232 I i CONTROL FOR 1.00 LETOFFS Oscar V. Payne, Leicester,Mass, assignor to Crompton & Knowles Loom Works, Worcester, Mass., acorporation of Massachusetts Application November 13, 1939, Serial No.304,157 11 Claims. (Cl. 139-110 This invention relates to improvementsin letolf mechanisms for looms and it is the general object of theinvention to provide means which will automatically relieve the warp andcloth of the strain imposed upon them by the letoff when the loom stops.

In those forms of letoff'mechanisms for looms which employ a weight orits equivalent there is generally present a backwardly-exerted strain onthe warp thread which resists the forward advance of the cloth by thetake-up mechanism, thereby maintaining desirable tension on the warpthreads. When very fine fabrics are being woven and the loom stands atrestfor any length of time a letoff of this type acts to draw the fellof the cloth rearwardly so that upon resumption of weaving the first fewpicks of weft to be laid are beaten in too closely to the picks laidimmediately before weaving stopped, thus producing a so-called thickplace. It is an important object of my present invention toprovidemechanism acting automatically and preferably controlled fromsome part which has a movement when the loom stops to prevent the letofffrom exerting sufficient rearward pull on the warp threads to changematerially the position of the fell of the cloth. a

In my prior Patent No. 1,803,143 I show a pawl which is moved manuallyinto holding position with respect to a rack secured to a part of theletoff mechanism which turns with the warp beam against the action of aweight. In that construction the pawl moves about a fixed axis and islikely to be located at a point between two teeth and unable to engageeither tooth until the weight has induced rearward turning of the warpbeam sufficient to move one tooth to the pawl. This rearward turning,however, disturbs the setting of the fell of the cloth and it is afurther object of my present invention to provide locking means for theletoif which moves to locking position immediately upon loom stoppagewithout requiring backward motion of the beam and regardless of theangular position of the ratchet. This result I accomplish as set forthhereinafter by moving the pawl bodily toward the ratchet a sufiicientdistance to insure engagement with one or another of the ratchet teeth.

In some instances the pawl will move only a short distance beforeengaging a tooth while in other instances the pawls will move aconsiderable distance before reaching locking position. I

The part of the loom which moves" when the loom stops, such for instanceas the shipper handle, moves through a definite distance which cannotordinarily be changed to accommodate the motion of the pawls bodilytoward the ratchet teeth. It is another object of my presentinvention toprovide a yielding element in the train of mechanism connecting theshipper handle with the letoff which can be adjusted to transmitsuficient force to lock the letofi' mechanism and then yield to permitfurther movement of the shipper handle.

With these and other objects in viewwhich will appear as the descriptionproceeds, my invention resides in the combination and arrangement ofparts hereinafter described and set forth.

In the accompanying drawings, wherein a convenient embodiment of myinvention is set forth:

Fig. 1 is a side elevational part of a loom showing a letoff and myimproved controller therefor in letoff locking position, I

Fig. 2 is a detail rear elevation taken in the direction of arrow 2,Fig. 1, I v

Fig. 3 is adetail horizontal section on line 3-3 of Fig. 1,

Fig. 4 is a detail plan looking in the direction of arrow 4, Fig. 1,

Figs. 5 and 6 are detail rear elevations looking in the directions ofarrows 5 andfi, respectively, Fig. 1, and

Figs. 7 and 8 are diagrammatical views showing themotion of the lockingpawls as they move relatively to the ratchet with respect to which theycooperate.

Referring to the drawings, particularly Fig. l, Ihave shown a loom frameIII in the forward part of which ismounted a shipper shaft II to whichis secureda shipper handle [2. An arm lit-secured to and depending fromthe shipper shaft moves to the left when the shipper handle is pulledforwardly or to the right as viewed in Fig. 1 to cause loom operation,and moves to the right when the shipper handle rocks in the oppositedirection to stop the loom.

Extending rearwardlly from'the loom frame is a bracket 15 on which ismounted a warp beam l6 supplying warp thread W extending forwardlytoward weaving instrumentalities not shown. Associated with the warpbeam is a letofi mechanism L having an arcuate segment I! fora cable orrope [8 the lower end of whichis attached to a variable weight I9. Theleto-fi' mechanism includes in its construction a plate 20on which are.cast a series of ratchet teeth 2| and a shaft 22 supported by the platehas keyed thereto a worm 23 which meshes with a worm Wheel 24 secured tothe warp beam. The gudgeon 25 of the warp beam rotates in a bearing 25supported by the bracket [5.

The particular form of letoff which I illustrate at the left part ofFig. 1 may be the same as that shown in my prior Patent No. 1,803,143and of itself forms no part of my present invention except as itcooperates with parts to be described hereinafter. It is thoughtsufficient for an understanding of my present invention to state thatrotation of the warp beam in a clockwise direction as viewed in Fig. lto unwind warp thread is accompanied by a corresponding rotation of wormgear 24 which transmits a force throughthe worm 23 to plate 23 to turnthe latter to the right and thereby raise the weight I9. When apredetermined amount of angular motion of the warp beam has occurredmechanism not shown herein but set forth in my prior mentioned patentacts to turn the worm in such a direction as will permit descent of theweight l9, after which said weight will again start to rise as more Warpthread is consumed.

The matter thus far described may be of the usual construction and ofitself forms no part of my present invention.

In carrying my present invention into effect I provide the bracket witha depending arm 30 onwhich a lever 3! is pivoted as at 32. An adjustablerod 33 pivoted to the lever at 34 extends forwardly and is pivoted at 35to arm l3 on the shipper shaft H. A slot 33 in arm I3 permits adjustmentof the pivot 35 toward and from the shipper shaft II.

The lower end of lever 3| is pivotally connected as at 43 to a rod guide4| having a sleeve 42 through which extends a rod 43. An adjustablecollar 44 on the rod 43 engages the forward end of the sleeve 42 tolimit rearward motion of the rod and also to cause the rod to moveforwardly when lever 3| rocks in a counterclockwise direction as viewedin Fig. 1. A compression spring 45 surrounds the rod 43 and extends fromthe rear end of the sleeve 42 to a second collar 43 adjustably securedon rod 43.

The locking mechanism for the letoff is operated by rod 43 and as set upmore particularly in Figs. 2, 3 and 4 comprises a stud 53 secured in thebracket l5 by set screw 5|. Mounted on this stud is the. eccentric hub52 of a lever 53 pivotally connected as at 54 to the rear end of rod 43.In the present instance I show a lock which, is adaptable to letoifmechanisms now in use having relatively large ratchet teeth, but for newconstructions the ratchet teeth could be smaller and use a single pawl.Mounted on the eccentric hub 52 as shown particularly in Figs. 2 and3are three pawls 55, and 55 and 51 of different lengths so that one oranother of them Will be able to engage a tooth 2! with a very smallmotion of the pawls toward the teeth. Each pawl has a small ear 30' anda light tension spring 5| the forward end of which is held by a wire 52connected to a link 63 the forward end of which may be attached-to thedepending arm 30. Each pawl also has a lug 65 for engagement with a stoppin 65 carried by lever 53. The springs of the several pawls hold theirrespective lugs 55 against the stop pin under normal operatingconditionsbut when the loom is stopped the pin 56 is moved away from the lugs 65so that the springs will tend to rock the pawls in a clockwise directionaround eccentric 52 and stud 53 as viewed inFig. 1 toward the ratchetteeth 2|.

In operation, the shipper handle will be pulled forwardly to start theloom and act through the connections described to move rod 43 to arelatively forward position by a force transmitted positively throughsleeve 42 and collar 44, thereby rocking lever 53 positively and movingthe stop pin against the lugs 65 to hold the pawls spaced from theratchet teeth 2| against the action of their springs 51. When in thisposition lever 53 is forward and the parts are as shown in full lines inFig. '7 and. the letoiT delivers warp in a manner already described.

When the loom is stopped the shipper handle and shipper shaft I [turn ina counter-clockwise direction to the position shown in Fig. 1 and movesleeve 42 rearwardly to compress spring 45. During this rearward motionof the sleeve 42 force is transmitted yieldingly through spring 45 andcollar 45 to move the rod 43 in a backward direction and rock lever 53rearwardly or in a clockwise direction. When the parts reach the dottedline position in Fig. 7 the pawls are in engasemjentwith the teeth 2!.

The pawls can move toward the ratchet while theratchet teeth are in anyone of a number of angular positions with respect to the axis of theletcff mechanism and there is no assurance that any one of the pawlswill be in position for immediate engagement with a tooth shoulder 10.Assuming as one condition of operation, however, that one of the pawlsis against a shoulder l0 as, shownin Fig. 7, continued rearward movementof sleeve 42 will cause compression of Spring 45 and this. compressionwill continue until the shipper handle has reached its. normal offposition. Thev spring 45 is relatively light and offers no.objectionable resistance to. the motion of the shipper handle. Underthis assumed condition, therefore, one of the pawls will be inengagement with a tooth to support weight l9 and spring 45 .willbesubjected to a relatively large compression.

Assuming on the other hand that when the pawls .move to the dotted lineposition of Fig. 7 none of them is sumciently near a shoulder 15 forimmediate holding engagement with the ratchet, continued rocking of theshipper handle will move the rod 43 rearwardly and rock the lever 53 tothe left from the dotted line position of Fig. 7. During this rockingof'lever 53 the wide part of the eccentric moves to the left and acts tomove the pawls bodily in a direction toward the ratchet. The extent ofthis motion of the pawls toward the ratchet will be sufficient becauseof the proportions of the eccentric to move one or another of the pawlsinto engagement with a shoulder 70. If this engagement occurs before theshipperhandle has reached its full off position there will be a slightcompression of spring 45 to accommodate the excess motion of the shipperhandle. In Fig. 8 the full line position corresponds to the dotted lineposition of Fig. 7, and the dotted line position corresponds to theextreme left hand position which lever 53 can occupy if the pawls havetobe moved bodily a considerable distance to cause engagement betweenone of them and a shoulder 10.

I find that the mechanical advantage due to the proportions of the lever53 and the eccentric are sufiiciently favorable to permit the use of alight spring 45 and that the latter will exert sufiicient rearward forceto prevent turning of the lever 53 by a force'transmitted from theshoulder and through a pawl to'the eccentric. In this connection it isinteresting to note that under the first assumption previously made theeccentric does not move very far and there -is a relatively large forcedirected from the'ratchet toward the eccentric tending to turn the lever53 in a counter-clockwise direction, but under this condition the spring45 is under a relatively high degree or compression and thereforeo-fiers considerable resistance to any turning of lever 53 which mightbe induced by the weight l9 acting through the ratchet; On the otherhand, under the second of the previously made assumptions the eccentricswings toward a position between stud 50 and the ratchet and the turningmoment acting on lever 53 is comparatively small and can be resisted bythe spring 45 even thoughthe latter is under a lesser degree ofcompression than that existing under the first assumption previouslymade. r. I l

From the foregoing it will be seen that I provide a look for the letofimechanism which is moved by some part of the loom which moves when theloom stops to a position to support weight l9 and prevent the latterfrom subjecting the warp threads to improper strains during periods ofidleness. It will also be seenthat the force which moves the lockingpawls into position is transmitted yieldingly through the spring 45,thereby making unnecessary fine adjustments to accommodate the motion ofthe shipper handle to the motion of the pawls. It will further be seenthat the eccentric acts to move the pawls toward the ratchet teeth 2|,thereby giving assurance that at least one of the pawls will be inholding position with respect to a tooth 2| when the shipper handle isin non-running position, thereby preventing any descent of weight l9.The mechanical advantage due to the eccentric enables a comparativelylight force exerted by spring 45 to support the weight [9 and preventrearward displacement of the fell of the cloth. Again, the stop pin 66serves topull the pawls out of locking position whenever the shipperhandle is moved to running position, but releases the pawls so that theycan be moved toward the ratchet teeth 2| bytheir springs as soon as theshipper handle moves away from running position.

It will also be seen that a compensating relation exists between thedegree of compression of spring 45 and the amount of angular motion onthe part of the eccentric, a position of the eccentric which permitsweight I9 to exert a relatively large force tending to turn lever 53being resisted by a high compression of spring 45, while a location ofthe eccentric so that a smallv turning force only can be exerted bytheweight on the lever 53 corresponds to a lighter degree of compressionof the spring 45.

Having thus described my invention it willbe seen that changes andmodifications may be made therein by those skilled in the art withoutdeparting from the spirit and scope of the invention and I do not wishto be limited to the details herein disclosed, but what I claim is:

1. In a loom having a part which moves when the loom stops and having aletoff mechanism provided with a member rotatable with the warp beamagainst the action of a weight as warp is consumed, the weight normallyexerting a continuous rearward force on the warp and cloth and tendingto cause reverse rotation of the member and beam, that improvementcomprising locking mechanism for the member normally in non-lockingposition, and means controlled by the part when the latter moves due toloom stoppage to move the locking mechanism into locking relation withrespect to the member and prevent reverse rotation of the latter by theweight.

2. In a loom having a stationary frame and a part which moves when theloom stops and having a letoif mechanism provided with a memberrotatable with the warp beam against the action of a weight as warp isconsumed, the weight normally exerting a continuous rearward force onthe warp and cloth and tending to cause reverse rotation of the memberand beam, that improvement comprising locking mechanism for the memberincluding a device movable with the member and a second device mountedon the stationary frame of the loom, said device normally disengaged,and means controlled by said part when the latter moves due to loomstoppage to cause cooperation between the two devices to prevent reverserotation of the member by the weight.

3. In a loom having a part which moves when the loom stops and having aletoff mechanism provided with a member rotatable with the warp beamagainst the action of a weight as warp is consumed, the weight normallyexerting a continuous rearward force on the warp and cloth and tendingto cause reverse rotation of the member and beam, that improvementcomprising a series of ratchet teeth movable with the member, a pawlnormally disengaged from the teeth, and means connecting said part andthe pawl to move the latter into engagementwith one of the teeth toprevent reverse rotation of the member by the weight when said partmoves due to loom stoppage.

4. In a loom having a part which moves when the loom stops and having aletofi mechanism provided with a member rotatable with the warp beamagainst the action of a weight as warp is consumed, the weight normallyexerting a continuous rearward force on the warp and cloth and tendingto cause reverse rotation of the member and beam, that improvementcomprisinga series of ratchet teeth movable with the member, a set ofpawls of different lengths normally disengaged from the teeth, and meansconnecting said part and the pawls to move the latter into engagementwith the series of teeth and to place one of said pawls in holdingrelation with respect to one of the teeth to prevent reverse rotation ofthe member by the weight when said part moves due to loom stoppage.

5. Ina loom having a part which moves a given distance when the loomstops and having a let- 'oif mechanism provided with a member rotatablewith the warp beam against the action of a weig t as warp is consumed,the weight normally exerting a continuous rearward force on the warp andcloth and tending to cause reverse rotation of the member and beam, thatimprovement comprising a lock for the member normally in nonlockingposition and movable from normal position through a distance less thansaid given distance to locking position with respect to the member,connections between said part and the lock movable by the part when thelatter moves due to loom stoppage to move the lock to locking positionwith respect to the member, and a yielding element in said connectionswhich yields after the lock is in locking position to accommodatecontinued motion thereafter by the part.

6. In a loom having a part which moves a given distance when the loomstops and having a 1etoif mechanism provided with a member rotatablewith the warp beam against the action of a weight as warp is consumed,the weight normally exerting a continuous rearward force on the warp andcloth and tending to cause reverse rotation of the member and beam, thatimprovement comprising a series of ratchet teeth secured to and movablewith the member, a pawl normally disengaged from the teeth and movableinto engaging, position relatively to the teeth, connections between thepawl and the part to move the pawl from normalpcsition to engagingposition with respect to one of the teeth when said part moves cluetozloom stoppage prior to the completion of motion of said part throughsaid distance, and a yielding element in the connections which yieldsafter the pawl has engaged one of the teeth to accommodate continuedmotion thereafter of said part.

'7. In a loom having a part which moves when the loom stops and having aletoff mechanism providedwith a member rotatable with the warp beamagainst the action of a weight as warp is consumed, the weight normallyexerting a con 1 tinuous rearward force on the warp and cloth andtending to cause reverse rotation of the member and beam, thatimprovement comprising an eccentric, a fixed pivotal mounting for theeccentric, a pawl pivoted on the eccentric, means operated by said partwhen the latter moves due to loom stoppage to turn the eccentric, meansmoving the pawl toward the member when the eccentric turns, and a seriesof ratchet teeth on the member to be engaged by the pawl to preventreverse rotation of the plate by the weight, the eccentric turning whenmoved by the connections to said part in a direction to move the pawlbodily toward and into engagement with one of the ratchet teeth.-

' 8. In a loom having a part which moves when the loom stops and havinga letoif mechanism provided with a member rotatable with the warp beamagainst the action of a weight as warp is consumed, the weight normallyexerting a continuous rearward force on the warp and cloth and tendingto cause reverse rotation of the member and beam, that improvementcomprising a series of ratchet teeth moving with the member, aneccentric connected to said part to be turned by the latter when saidpart moves due to loom stoppage, a pawl pivoted on the eccentric, a stopmoving with the eccentric normally holding the pawl out of engagementwith the teeth of the ratchet, yielding means acting to move the pawltoward the teeth when the stop turns with the eccentric away fromholding relation with respect to the pawl, said eccentric acting whenturned by said part to move the pawl bodily toward and into engagementith one of the teeth of the series.

9. In a loom having a part which moves when the loom stops and having aletoif mechanism provided with a member rotatable with the warp beamagainst the action of a Weight as warp is consumed, the weight normallyexerting a continuous rearward force on the warp and cloth and tendingto cause reverse rotation of the member and beam, that improvementcomprising a series of ratchet teeth moving with the member, aneccentric connected to the part to be turned by the latter when the samemoves due to loom stoppage, a pivotal support for the eccentric, thelatter having narrow and wide parts on opposite sides of the pivotalsupport, a pawl pivotally mounted on the eccentric and normally heldaway from the series of teeth when the loom is running, means to movethe pawl toward the teeth by a pivotal motion around the eccentric whenthe latter turns at the time of loom stoppage, the wide part of theeccentric moving toward a position between the pivotal support for theeccentric and the series of ratchet teeth when said part turns theeccentric to give the pawl a movement bodily in a direction from thepivotal support for the eccentric toward the series of teeth.

10. In a loom having a part which moves when the loom stops and having aletoff mechanism provided with a member rotatable with the warp beamagainst the action of a weight as warp is consumed, the weight normallyexerting a continuous rearward force on the warp and cloth and tendingto cause reverse rotation of the member and beam, that improvementcomprising locking mechanism for the member normally innon-lockingrelation with respect to the member, and means controlled bythe part when the latter moves due to loom stoppage to move the lockingmechanism into locking relation with respect to the member to preventreverse rotation of said member by the weight.

11. In a loomvhaving a part which moves a given distance when the loomstops and having a letoff mechanism provided with a member rotatablew-iththe warp beam against the action of a weight as warp is consumed,the weight normally exerting a continuous rearward force on the warpandlcloth and tending to cause reverse rotation of the member and beam,that improvement comprising a series of ratchet teeth secured to andmovable with the member to any one of a plurality of difierentpositions, a pawl normally disengaged from the teeth, an eccentric onwhich the. pawl is pivotally mounted, :a pivotal support for theeccentric, the latter having narrow and wide parts on opposite sides ofthe pivotal support, connections between the said part and the eccentricto move the Wide part of the eccentric toward a line joining the pivotalsupport and the ratchetteeth when said part moves at the time of loomstoppage, means to move the pawl against the ratchet when the eccentricis moved by said part, and a yielding element in said connectionsyieldingly transmitting, from said part to the eccentric a force whichincreases with increased yielding of said element and yielding when thepawl engagesa tooth before said part completes movement through saidgiven distance, said element transmitting a considerable force from thepartto be-exerted on the eccentric when the pawl engagesa ratchet toothafter a small amount of turning of the eccentric and the wide part ofthe eccentric has turned a small angular distance toward said line, andsaid element transmitting a smaller force from the part to the eccentricwhen the pawl engages a ratchet tooth after a larger amountof turning ofthe eccentric and the wide part of the eccentric has turned through alarger angular distance toward said line.

OSCAR V. PAYNE.

